How do you manage chaos as a DPS?

I've been a tank or healer for like, most of my WoW career at this point. Gotten to 3k multiple times in m+. I decided to try dps, and it's been really fun so far! Executing my rotation perfectly and getting that big DPS is chef's kiss... but the times I get to actually do that are pretty low. Tank moves crazy all of a sudden. Someone doesn't interrupt something. Something forces me to move and interrupt what I'm doing and then I forget where I was. So, career DPS, tell me your secrets. How are you managing this chaos and still maintaining big damage?